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Healthy 1 st degree IBD relatives Pre-UC Post-UC Matched HC Follow-up Proteolytic activity Microbiotahumanized mice Proteolytic activity Low-grade colonic inflammation Fecal proteolytic activity as early biomarker Microbiota composition BACKGROUND & AIMS: Altered gut microbiota composition and function have been associated with inflammatory bowel diseases, including ulcerative colitis (UC), but the causality and mechanisms remain unknown. METHODS: We applied 16S ribosomal RNA gene sequencing, shotgun metagenomic sequencing, in vitro functional assays, and gnotobiotic colonizations to define the microbial composition and function in fecal samples obtained from a cohort of healthy individuals at risk for inflammatory bowel diseases (pre-UC) who later developed UC (post-UC) and matched healthy control individuals (HCs). RESULTS: Microbiota composition of post-UC samples was different from HC and pre-UC samples; however, functional analysis showed increased fecal proteolytic and elastase activity before UC onset. Metagenomics identified more than 22,000 gene families that were significantly different between HC, pre-UC, and post-UC samples. Of these, 237 related to proteases and peptidases, suggesting a bacterial component to the pre-UC proteolytic signature. Elastase activity inversely correlated with the relative abundance of Adlercreutzia and other potentially beneficial taxa and directly correlated with known proteolytic taxa, such as Bacteroides vulgatus. High elastase activity was confirmed in Bacteroides isolates from fecal samples. The bacterial contribution and functional significance of the proteolytic signature were investigated in germ-free adult mice and in dams colonized with HC, pre-UC, or post-UC microbiota. Mice colonized with or born from pre-UC-colonized dams developed higher fecal proteolytic activity and an inflammatory immune tone compared with HC-colonized mice. CONCLU-SIONS: We have identified increased fecal proteolytic activity that precedes the clinical diagnosis of UC and associates with gut microbiota changes. This proteolytic signature may constitute a noninvasive biomarker of inflammation to monitor at-risk populations that can be targeted therapeutically with antiproteases.

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Elevation of both ALT and GGT within 90 days after the diagnosis of IBD is associated with a markedly increased likelihood of IBD-LD. Both ALT and GGT levels should be measured in all of the pediatric patients newly diagnosed as having IBD.

Aim-To characterize rectal histology in an inception cohort of children newly diagnosed with ulcerative colitis (UC) and to explore its relationship with clinical indices of disease severity.

In autoimmune liver disease (AILD), including autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and overlap syndrome of AIH and PSC (ASC), the presence of biliary injury portends a worse prognosis. We studied serum matrix metalloproteinase 7 (sMMP7) as a biomarker for pediatric sclerosing cholangitis (SC). We prospectively enrolled 54 children (median age, 16 years) with AILD (AIH, n = 26; ASC, n = 16; and PSC, n = 12) at our center. The sMMP7 concentrations were higher in patients with SC compared to those without cholangiopathy ( P < 0.001). An sMMP7 concentration >23.7 ng/mL had a sensitivity and specificity of 79% and 96%, respectively, and outperformed alkaline phosphatase (ALP) and gamma‐glutamyltransferase (GGT) in segregating patients with SC. Serum concentrations correlated with liver gene expression levels for MMP7 ( r = 0.70; P < 0.001). Using immunofluorescence, MMP7 was localized primarily to the cholangiocytes of patients with SC. In 46 subjects with liver biopsy available for blinded review, elevation in sMMP7 concentrations segregated with the presence of lymphocytic and neutrophilic cholangitis and periductal fibrosis and correlated with Ishak, Ludwig, and Nakanuma scoring systems. Liver stiffness measured by magnetic resonance elastography also correlated with sMMP7 concentrations ( r = 0.56; P < 0.01). Using magnetic resonance cholangiopancreatography plus (MRCP+), sMMP7 in 34 patients correlated with the number of biliary dilatations ( r = 0.54; P < 0.01) and strictures ( r = 0.56; P < 0.01). MMP7 as a marker of biliary injury was validated in an independent cohort of children with ulcerative colitis. Higher sMMP7 concentrations also correlated with a history of SC‐related complication. Conclusion : MMP7 is a promising biomarker for pediatric SC that diagnostically outperforms ALP and GGT. sMMP7 may directly reflect biliary injury and fibrosis, the main drivers of disease progression in SC.